Mystery Volcano Photo #24

Mystery Volcano Photo #23 was, in fact, Middle Sister volcano in Oregon, part of the picturesque Three Sisters near Bend. Middle Sister is a partially eroded (by glaciers) composite volcano with a mix basaltic andesite to andesite lava flows and tephra deposits. Depending on who you speak with, Middle Sister gets lumped in with North Sister (as Middle Sister build up on the flanks of its slightly older sibling) or stands on its own as a part of the Three Sisters. However, before thinking Middle Sister is dormant, remember, the last eruption might have been as recent as ~440 A.D.

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